With multiple antennas, performance of a wireless communication system can be greatly improved. If not only spatial characteristics of the local cell signal, but those of interference signals of other cells are taken into account in space-time processing of a multi-antenna system, the system performance will be further improved. Said space-time processing can be implemented only when the space correlation characteristics of noise (including heat-noise and interference) have been measured and estimated, i.e. when the space correlation matrix of noise has been given. In P. Jung and J. Blanz, “Joint Detection with Coherent Receiver Antenna Diversity in CDMA Mobile Radio Systems” IEEE Trans. Veh. Tech., vol. 44, pp. 76-88, February 1995, functions and characteristics of a noise space correlation matrix in a time-slotted CDMA system with smart antenna have been discussed. Nevertheless, when implementing and emulating the technique described in the document, it is assumed that noises are not mutually correlation, i.e. without taking into account the correlation characteristics of the noises. No method for estimating the noise space correlation matrix is provided, either. In practice, the signal to be received is accumulated with the noise, i.e. e=s+n, where e is the total received signal, s is the signal component and n is the noise component. In a practical measurement and estimation of the correlation characteristics of noise, it is usually assumed that the noise component is of Gaussian distribution and uncorrelated with the signal component, so the following formula exists:E{n·n*T}=E{e·e*T}−E{s·s*T}
Analysis and emulation results show that the above estimation algorithm of the noise space correlation matrix will be rather instable when the signal-to-noise ratio increases, making the error code rate worse rapidly. Thus, the above estimation algorithm does not satisfy the system requirement in a practical range of the signal-to-noise ratio.